Seok, 46, who defected to the South in 1998, is known for practicing North Korea’s “royal court medicine” that he learned while working at Pyongyang’s top medical research center devoted solely to caring for the health of leader Kim Jong-il.

The research institute is known in South Korea as the Kim Il-sung Longevity Research Institute after the name of the North’s late national founder and father of the current leader. Among North Koreans, it is simply called the “long life research institute,” Seok said, dressed in a white lab coat during a recent interview at his two-story clinic.

“Simply put, the long life research institute is to look after the general,” Seok said, referring to the North’s leader. “I was with the cardiovascular and anti-aging team at the institute.”

Details about the secrecy-shrouded Basic Medicine Research Center in Pyongyang are scarce, but the institute was believed to have hundreds of herbal doctors, physicians, biologists and other scientists working to make sure that the North Korean leader lives for a long time and in good health, Seok said.

Newly developed treatment methods, Seok said, were first tested on people similar to the leader in age and body type and with heart disease, an illness that killed late leader Kim Il-sung in 1994 and the current leader Kim Jong-il, now 68, is believed to be suffering from.

“These people were considered lucky because they were treated with good medicine,” Seok recalled.

Besides medical research, the longevity institute was also charged with growing high-quality organic rice, fruits and other agricultural products for the leader, even burying dogs in the farm fields as fertilizer, he said.

A top graduate from the North’s prestigious Pyongyang Medical College, Seok said he was plucked by authorities and assigned the research center regardless of his desires. Most graduates wanted to work at general hospitals where they could make more money.

“It’s not a place you can apply to work at. It’s a place you are dragged into,” Seok said with a chuckle that appears to imply a sense of relief that he is no longer in the totalitarian nation and lives a happy life in South Korea.